Analysis of femtosecond laser assisted capsulotomy cutting edges and manual capsulorhexis using environmental scanning electron microscopy.

Purpose. To investigate the structure and irregularity of the capsulotomy cutting edges created by two femtosecond (FS) laser platforms in comparison with manual continuous circular capsulorhexis (CCC) using environmental scanning electron microscopy (eSEM). Methods. Ten anterior capsulotomies were obtained using two different FS laser cataract platforms (LenSx, n = 5, and Victus, n = 5). In addition, five manual CCC (n = 5) were obtained using a rhexis forceps. The specimens were imaged by eSEM (FEI Quanta 400, OR, USA). Objective metrics, which included the arithmetic mean deviation of the surface (Sa) and the root-mean-square deviation of the surface (Sq), were used to evaluate the irregularity of both the FS laser capsulotomies and the manual CCC cutting edges. Results. Several microirregularities were shown across the FS laser capsulotomy cutting edges. The edges of manually torn capsules were shown, by comparison of Sa and Sq values, to be smoother (P < 0.05) than the FS laser capsulotomy edges. Conclusions. Work is needed to understand whether the FS laser capsulotomy edge microirregularities, not seen in manual CCC, may act as focal points for the concentration of stress that would increase the risk of capsular tear during phacoemulsification as recently reported in the literature.

Optimal parameters to improve the interface quality of the flap bed in femtosecond laser-assisted laser in situ keratomileusis.

PURPOSE: To analyze the interface quality of the anterior stroma after femtosecond laser flap creation using atomic force microscopy. SETTING: IRCCS Fondazione G.B. Bietti, Rome, Italy. DESIGN: Experimental study. METHODS: A 110 µm depth flap was created in 20 human corneal tissues using a femtosecond laser platform (Intralase iFS). Tissues were divided into 4 groups of various cutting parameters: pulse energy and spot separation of 0.75 µJ and 6 µm (Group 1), 0.65 µJ and 5 µm (Group 2), 0.55 µJ and 4 µm (Group 3), and 0.45 µJ and 4 µm (Group 4). Four additional tissue sections were cut using a motorized microkeratome (Hansatome). Atomic force microscopy (Autoprobe CP) analysis was performed on the stromal bed of each sample. RESULTS: The corneal tissues treated with higher pulse energies and wider spot separations (Groups 1 and 2) showed a rougher stromal bed interface (root mean square [RMS] rough = 0.23 µm ± 0.008 (SD) and 0.24 ± 0.009 µm, respectively) than tissues in Groups 3 and 4 (RMS rough = 0.18 ± 0.006 µm and 0.18 ± 0.008 µm, respectively; P<.001, 1-way analysis of variance). The stromal surface quality of tissues treated with pulse energies of 0.55 µJ or lower and 4 µm spot separation compared favorably with that of tissues cut by the microkeratome (RMS rough = 0.17 ± 0.006 µm; P>.05, Tukey). CONCLUSIONS: The femtosecond stromal interface quality was improved with pulse energy lower and spot separations narrower than those currently used in the clinical setting. The flap interface smoothness created by the femtosecond laser was comparable to that created by the microkeratome. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Sixty-kilohertz femtosecond laser-assisted endothelial keratoplasty: clinical results and stromal bed quality evaluation.

PURPOSE: To evaluate preliminary clinical results and lamellar and side cut obtained with a 60-kHz femtosecond laser (IntraLase) using a new software designed to create penetrating cuts for keratoplasty to perform the donor and recipient dissection in femtosecond laser-assisted endothelial keratoplasty. DESIGN: Prospective interventional case series. METHODS: A femtosecond laser set in a raster spot pattern was used to create the posterior lamellar dissection and posterior side cut in 4 donor corneas and in 4 recipient human eyes of 4 patients with endothelial decompensation. The laser cut was performed to obtain a 150-µm thick and 9-mm wide posterior lamellar disk from the donor and the recipient eyes. Postoperatively, patients underwent slit-lamp examination and Snellen visual acuity evaluation, Visante optical coherence tomography, optical pachymetry, and endothelial microscopy analysis. Three residual donor corneas were analyzed by scanning electron microscopy and transmission electron microscopy to observe the stromal bed surface, the side cut, and the effects of the laser dissection on the cornea ultrastructure. MAIN OUTCOME MEASURES: Thickness of the implanted donor lamella, adhesion and clarity of the transplanted cornea in the postoperative follow-up, and smoothness of the interface. RESULTS: All the patients showed good adhesion and fit of the donor disk to the recipient and a circle side cut observed at the slit-lamp examination. Visante optical coherence tomography evaluation confirmed the adhesion and the precalibrated thickness of the implanted lamella. A good corneal transparency was achieved within the first 2-3 weeks. The scanning electron microscopy analysis showed a smooth stromal residual surface and a precise side cut. The transmission electron microscopy images showed that the laser randomly modified the structural design of the collagen fibers for approximately 10-µm depth, although below a regular stromal structure was maintained. CONCLUSIONS: The 60-kHz IntraLase femtosecond laser creates a smooth stromal bed and precise side cut for endothelial keratoplasty. The posterior lamellar cut performed at the same depth in both the donor and the recipient makes it possible to create a corneal disk from the donor that fits exactly with the cut in the recipient.

The use of the femtosecond laser in penetrating keratoplasty.

PURPOSE: To evaluate a new technique for penetrating keratoplasty (PK) with the use of a new software algorithm for a femtosecond laser that is designed to create penetrating cuts for PK in the treatment of a number of corneal diseases. DESIGN: Prospective, interventional case series. METHODS: All eyes were treated at the Ospedale Civile di Mestre, Umberto, Italy. Seven eyes of seven patients underwent surgery for PK using a 15-kHz femtosecond laser (IntraLase, Irvine, California, USA) and a new software specifically developed for corneal surgery. Of the seven patients, five were keratoconus patients and two had bullous keratopathy. New software was used to create penetrating cuts in a top hat or mushroom configuration. After surgery, all patients were evaluated with pachymetry, corneal topography, refraction, intraocular pressure measurement, and corneal optical coherence tomography (Visante; Carl Zeiss, Oberkochen, Germany). RESULTS: On postoperative day one, all seven eyes had nearly clear corneas with a good graft of the donor corneas to the patients' corneas. At three months, all eyes had clear corneas with good endothelial cell counts and quiet anterior chambers. Normal corneal thickness was achieved in each case. At the three-month visit, suture removal was performed in five eyes to adjust for astigmatism. CONCLUSIONS: Although this is a small number of eyes, early indications are that the use of the new IntraLase software for corneal surgery creates a more favorable environment for PK as a result of a better fit of the donor cornea and a quicker visual recovery for patients.

Visual acuity and contrast sensitivity comparison between Tecnis and AcrySof SA60AT intraocular lenses: A multicenter randomized study.

PURPOSE: To evaluate best corrected visual acuity (BCVA) and photopic and mesopic contrast sensitivity in pseudophakic patients implanted either with the aspheric intraocular lens (IOL) designed to correct for corneal spherical aberration or with a conventional IOL. SETTING: Three surgical centers participated this prospective randomized masked comparative study. METHODS: Thirty eyes of 30 patients after aspheric lens implantation (Pfizer/Pharmacia Tecnis Z9000) were compared with 30 eyes of 30 age-matched patients after conventional lens implantation (Alcon AcrySof SA60AT). Two to three months after surgery, best spectacle corrected distance visual acuity was measured using the Early Treatment Diabetic Retinopathy Study chart. Contrast sensitivity was measured by sinusoidal grating charts for distance at photopic (85 cd/m(2)) and mesopic (6 cd/m(2)) luminance level with optical correction in place. Tested spatial frequencies were 1.5, 3, 6, 12, and 18 cycles per degree (cpd). RESULTS: The mean BCVA was -0.053 +/- 0.044 logMAR in eyes with the aspheric Tecnis IOL and 0.006 +/- 0.059 logMAR in eyes with the conventional AcrySof IOL (P=.0001). Eyes with the aspheric IOL showed better contrast sensitivity at spatial frequencies of 3 cpd (P<.05) and 6, 12, and 18 cpd (P<.01) in photopic and in mesopic conditions. Peak improvement occurred at 18 cpd and was 36% (0.29 log units) in photopic and 54% (0.27 log units) in mesopic conditions. CONCLUSIONS: The aspheric Tecnis IOL yielded better BCVA and better distance contrast sensitivity than the conventional IOL. The differences were clinically significant for higher spatial frequencies. The results give some suggestions for further studies.